After 1978, two strangely related things happened: a new set of regulations for processed meat limited the amount of nitrite used in hot dogs, forcing manufacturers to add ascorbate or erythorbate instead. And the following that year, there was a major dropoff in colon cancer deaths. Now, researchers are questioning the link between the two.

Nitrite preserved processed meats are loaded with nonvolatile N-nitroso compounds, but the addition of ascorbate and erythorbate replaced them, with only 1/90th of the amount remaining afterwards. There has been a significant amount of work on the link to processed meat with colorectal cancer, especially with the presence of nitrates and nitrites. The thing is that if this correlation was iron clad, then the there would have been a huge drop in the incidence of the cancer with the government regulation. Instead, there's been a major drop in the deaths from the disease — which is something very different. So while fewer people are dying of colon cancer, the drop in nitrites doesn't seem to have meant fewer people getting it.

"The drop in N-nitroso compound content caused by the mandated changes in processed meat should have been accompanied by a drop in the incidence of colon cancer," said Professor Sidney S. Mirvish, and the reduction in deaths "may have been due mostly to earlier detection and better treatment of this disease."

UPDATE: An earlier version of this article significantly misinterpreted part of the study — which was my mistake. It has been updated and corrected. Apologies.